A machine tool processes a workpiece by relatively moving, in three orthogonal axes directions of X-, Y- and Z-axes, a workpiece attached to a table and a tool attached to the end of a spindle. In the field of machine tools, in order to increase accuracy, error measurement methods using a laser beam have been developed.
For example, Patent Document 1 describes a laser tracking-type measuring device for tracking the travel of a reflector attached to a tool mounting shaft in order to detect the coordinate of a tool based on the displacement of the tracked reflector.